Multi-stage filter element

ABSTRACT

Multi-stage filtration apparatus is provided. A fluid is forced through different filter stage elements allowing for removal of various contaminants from the fluid.

FIELD OF THE INVENTION

This invention generally relates to filters, and more specifically tofilters in multi-stage vessels.

BACKGROUND OF THE INVENTION

Multi-stage vessels for filtration of various fluids are known. Filterelements may be mounted into an apparatus having multiple compartments,as shown, for example in U.S. Pat. Nos. 5,919,284 and 6,168,647, bothassigned to Perry Equipment Corporation, the disclosures of which areincorporated by reference herein in their entirety.

BRIEF SUMMARY OF THE INVENTION

In one aspect, a multiple stage filter element assembly is provided. Themultiple stage filter element assembly includes a first filter element.The first filter element comprises a first tube of filter mediasurrounding a longitudinal axis. The multiple stage filter elementassembly also includes a second filter element. The second filterelement includes a second tube filter media surrounding a longitudinalaxis when assembled with the first filter element. The first filterelement may be adapted to axially abut the second filter element with aninternal flow passage therebetween. The multiple stage filter elementassembly includes a first seal for the first filter element. Themultiple stage filter element assembly also includes a second seal forthe second filter element. The first and second seal elements may beadjacent each other proximate an interface between the first and secondfilter elements when in abutting relation.

According to the above aspect, each filter element may include its ownseal to seal against the guide tube in the housing. According to anembodiment, no physical connection may be needed between two elements,but rather they may be placed proximate and may further be in abuttingand/or interfitting relation. The high pressure side of the vessel maybe used to keep the abutting relation. Further, an intermediate pressurechamber may be formed between seals that is generally static duringoperation.

Alternatively, one of the filter elements may employ two seals with thesecond seal sealing between the filter elements. The second seal mayalso be pressure actuated such as an axial seal between filter element.

In one embodiment, the multiple stage filter element assembly may alsoinclude a first end cap. The first end cap encloses one end of the firstfilter assembly. The first end cap may have a first locating post. Themultiple stage filter element assembly may also include a second endcap. The second end cap encloses one end of the second filter element.The second end cap may have a second locating post on an opposite sideof the assembly as compared with the first locating post.

The first and second seal elements may be in surrounding relation of thefirst and second filter elements respectively. The first and secondseals may each be radial seals adapted for sealing against a commoninternal surface of a cylindrical guide of a tube sheet.

At least one of the first and second tubes of filter media may have anuncapped end surface at the interface. In one embodiment each of thetubes of filter media has an uncapped end surface at the interface.

The multiple stage filter element assembly may also include a first endcap sealing the end surface of one of the first and second tubes offilter media at the interface. The first end cap may include a firstannular guide portion extending transversely from the first end capalong a portion of the interior surface of the other of the first andsecond tubes of filter media. The multiple stage filter element assemblymay also include an second end cap sealing the end surface of the otherof the first and second tubes of filter media at the interface. Thesecond end cap may include a second annular guide portion configured tocooperatively threadably engage the first annular guide portion.

In one embodiment, the first and second filter elements may be arrangedin axially abutting end to end relation and may be mounted to eachother. In one embodiment, the first and second filter elements are notpermanently attached but readily removable from each other.

In one embodiment, the first and second tubes of the multiple stagefilter element assembly each have a length of between 1 and 4 feet. Thefirst and second tubes may be generally cylindrical with an outerdiameter of between 2 and 6 inches. The first and second tubes may alsohave an inner diameter of between 1 and 5 inches.

In one embodiment, the multiple stage filter element assembly alsoincludes a third filter element comprising a third tube of filter mediacoaxial with and enclosing at least a portion of the first tube offilter media. The third tube of filter media may be a type of filtermedia different than at least one of the first tube of filter media andsecond tube of filter media.

In another aspect of the present invention, a multiple stage filtrationvessel is provided. The multiple stage filtration vessel includes aclosed vessel having a longitudinally extending length and having aninitially open interior. The closed vessel also includes an inlet at anextent and an outlet at an opposite extent thereof. The multiple stagefiltration vessel also includes a partition located within the vesselinterior. The partition divides the vessel interior into a first stageand a second stage. The multiple stage filtration vessel also includes agenerally cylindrical guide. The generally cylindrical guide defines anopening in the partition. The multiple stage filtration vessel alsoincludes a filter element assembly. The filter element assembly extendsthrough the opening. The filter element assembly has a hollow corewherein flow passage through the multiple stage filtration vessel isprovided. A gas stream flows into the first stage through the inlet,into and through the hollow core of the filter element assembly, backout through the filter element assembly into the second stage to theoutlet. The filter element assembly includes an inner filter media tubeand an outer filter media sleeve at the first stage. The outer filtermedia sleeve surrounds the inner filter media tube. The outer filtermedia sleeve may be more open and porous than the inner filter mediatube.

In one embodiment, at least one of the outer filter media sleeve and theinner filter media tube may be a pleated filter member. In anotherembodiment, the inner filter media tube and the outer filter mediasleeve may each be formed from non-pleated depth filtration mediashaving a radial thickness of at least 0.20 inches.

In one embodiment, the inner filter media tube may extend a full lengthof a filtration chamber within the open interior between the extents.The outer filter media sleeve makes then a partial length only to thepartition. A seal sealing the filter element assembly to the generallycylindrical guide may also be included.

In another embodiment, the multiple stage filtration vessel alsoincludes a third filter media sleeve. When assembled with the innerfilter media tube, the third filter media sleeve may be adapted toaxially abut the inner filter media tube with an internal flow passagetherebetween.

In another embodiment, a multiple stage filtration vessel is provided.The multiple stage filtration vessel includes a closed vessel having alongitudinally extending length. The closed vessel includes an initiallyopen interior. The closed vessel also includes an inlet at an extent andan outlet at an opposite extent thereof. The multiple stage filtrationvessel also includes a partition located within the vessel interior. Thepartition divides the vessel interior into a first stage and a secondstage. The multiple stage filtration vessel also includes a generallycylindrical guide to finding an opening in the partition. The multiplestage filtration vessel also includes a filter element assembly. Thefilter element assembly extends through the opening. The filter elementassembly has a hollow core wherein flow passage through the multiplestage filtration vessel is provided. A gas stream flows into the firststage through the inlet, into and through the hollow core of the filterelement assembly, and back out through the filter element assembly intoa second stage to the outlet. The filter element assembly includes afirst filter element. The first filter element includes a first tube offilter media surrounding a longitudinal axis. The filter elementassembly also includes a second filter. The second filter elementincludes a second tube of filter media surrounding a longitudinal axis.When the first filter element and second filter element are assembled,the first filter element and the second filter element form an internalflow passage therebetween through the hollow core. The first and secondfilter elements are independent and readily attachable and detachablefrom each other. Each of the filter elements is directly or indirectlysupported by the generally cylindrical guide.

Yet another aspect is directed toward a three stage filter element. Thefilter element includes a first stage including a prefilter. The firststage also includes a portions of a continuous tubular filter elementarranged inside of the prefilter. An annular seal may be disposed aboutthe continuous tubular filter element to establish a second stage. Theprefilter may extend only a portion of the length of the continuousfilter element. This can provide a greater holding capacity at theupstream side of the filter element. The prefilter can be more open andof a lower efficiency than the continuous tubular element.

Other aspects, objectives and advantages of the invention will becomemore apparent from the following detailed description when taken inconjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings incorporated in and forming a part of thespecification illustrate several aspects of the present invention and,together with the description, serve to explain the principles of theinvention. In the drawings:

FIG. 1 is a partial cross-sectional view of an embodiment of amulti-stage vessel;

FIG. 2 is a partial cross-sectional view of another embodiment of amulti-stage vessel;

FIG. 3 is a condensed view illustrating embodiments of filter end caps;

FIG. 4 is an isometric view of an embodiment of a cap portion;

FIG. 5 is a cross-sectional view of the cap portion taken along line 5-5in FIG. 4;

FIG. 6 is a cross-sectional view of an embodiment of a multiple stagefilter element assembly mounted in an exemplary vessel;

FIG. 6A is an enlarged detail view of FIG. 6;

FIG. 6B is an enlarged detailed cross-sectional view of the ring sealholder and ring seal of FIG. 6A, which ring seal and seal holder mayalso be used in other embodiments;

FIG. 6C is a cross-sectional view of an embodiment of a multiple stagefilter element assembly mounted in an exemplary vessel illustrating aninternal element support core;

FIG. 6D is an enlarged detail view of FIG. 6;

FIG. 7 is a cross-sectional view of a second embodiment of a multiplestage filter element assembly mounted in an exemplary vessel;

FIG. 7A is an enlarged detail view of FIG. 7;

FIG. 7B is an isometric view of an embodiment of the ring divider sealend cap of FIGS. 7 and 7A;

FIG. 7C is a cross-sectional view of an alternate embodiment of amultiple stage filter element assembly mounted in an exemplary vessel;

FIG. 7D is an enlarged detail view of FIG. 7;

FIG. 8 is a cross-sectional view of a third embodiment of a multiplestage filter element assembly mounted in an exemplary vessel;

FIG. 8A is an enlarged detail view of FIG. 8;

FIG. 8B is an isometric disassembled view of an embodiment of the ringdivider seal end cap and the second filter element end cap of FIGS. 8and 8A cooperatively engageable therewith shown in semi-cross-section toillustrate the threading;

FIG. 9 is a cross-sectional view of a fourth embodiment of a multiplestage filter element assembly mounted in an exemplary vessel;

FIG. 9A is an enlarged detail view of FIG. 9;

FIG. 9B is an isometric view of an embodiment of the ring divider sealend cap of FIGS. 9 and 9A;

FIG. 10 is a partial cross-sectional view of the filter element of FIGS.9A and 9B mounted on an alternate end cap with a portion of the filterelement removed;

FIG. 11 is an enlarged detail view of FIG. 10;

FIG. 12 is a cross-sectional view of a fifth embodiment of a multiplestage filter element assembly mounted in an exemplary vessel;

FIG. 12A is an enlarged detail view of FIG. 12;

FIG. 13 is a cross-sectional view of a sixth embodiment of a multiplestage filter element assembly mounted in an exemplary vessel;

FIG. 13A is an enlarged detail view of FIG. 13;

FIG. 13B is an isometric view of an embodiment of a ring divider sealend cap of FIGS. 13 and 13A;

FIG. 14 is a cross-sectional view of a seventh embodiment of a multiplestage filter element assembly mounted in an exemplary vessel; and

FIG. 14A is an enlarged detail view of FIG. 14.

While the invention will be described in connection with certainpreferred embodiments, there is no intent to limit it to thoseembodiments. On the contrary, the intent is to cover all alternatives,modifications and equivalents as included within the spirit and scope ofthe invention as defined by the appended claims.

DETAILED DESCRIPTION OF THE INVENTION

As will be appreciated, multi-stage filtration may be used in varioussuitable applications. Exemplary filtration applications using variousembodiments of a multi-stage filter assembly 10 are described below withreference to the drawings.

Embodiments of multi-staged filter elements of the present invention maybe used to improve the apparatuses described in U.S. Pat. Nos. 5,919,284and 6,168,647 or may be used with various other suitable apparatuses toprovide improved multi-stage filtration.

With reference to FIG. 1, an exemplary multi-stage vessel 20 with whichan embodiment of a multi-stage filter assembly 10 may be used isillustrated. In such a multi-stage vessel 20, a fluid containing variouscontaminants may be filtered in various stages, as will be furtherdescribed below.

In one embodiment, the vessel 20 includes an inlet 22 and an outlet 24.The relationship of various elements in this disclosure will bedescribed in terms of “upstream” and “downstream.” For purposes of thisdisclosure, “upstream” will mean more proximate the inlet 22 in thefluid flow path (as will be further described below) and “downstream”will mean more proximate the outlet 24 in the fluid flow path.

With further reference to FIG. 1, the inlet 22 is in fluid communicationwith a first stage 26 defined within the vessel 20. A tubesheet 28generally divides the first stage 26 from a second stage 30, definedwithin the vessel 20, and is provided with a plurality of annular guides32 providing passage from the first stage 26 to the second stage 30. Theannular guides 32 are each configured to receive an embodiment of amulti-stage filter assembly 10, as will be further described below.Additionally, the annular guides 32 may be integrally formed as a singlepiece with the remainder of the tubesheet 28 or may be formed separatelyand attached to the dividing wall and partition 66 of the tubesheet 28by any suitable means such as metal welds.

The tubesheet 28 provides a generally fluid-tight seal around theinterior of the vessel 20 between the first stage 26 and the secondstage 30. The second stage 30 is in fluid communication with the outlet24. The partition and tubesheet 22 thereby divide the vessel into a highpressure side at the inlet and a low pressure side at the outlet, with apressure differential between sides typically between 0.1 and 20.0 PSIin most applications; and with a total pressure (on the inlet side)experienced in the vessel 20 during operation ranging from a vacuum toabout 10,000 PSI. The pressure vessel 20 and components thereof willtypically be rated to at least handle 2,000 PSI for many applications,and certainly rated higher (e.g. up to 10,000 PSI to 20,000 PSI orhigher for more intense applications).

As will be more fully explained below, a plurality of cylindrical firststage filter elements 34 each having a hollow core, a first end 36, anda second end 38 extend through the first stage 26 of the vessel 20. Thefirst ends 36 of the first stage filter elements 34 are located in theupstream portion of the first stage 26. The first stage filter elements34 extend downstream through the first stage 26 into the tubesheet 28where the second ends 38 of the first stage filter elements 34 are eachreceived into and supported by the upstream portion of one of theannular guides 32.

A corresponding plurality of cylindrical second stage filter elements 40each having a hollow core, a first end 42, and a second end 44 areprovided within the second stage 30. The second ends 44 of the secondstage filter elements 40 are each received the downstream portion of oneof the annular guides 32. The second stage filter elements 40 extendcoaxially with respect to first stage filter elements 32 from thetubesheet 28 through the second stage 30, and are each mounted proximatetheir first end 42 proximate the downstream portion of the second stage30. The first and second stage filter elements 34, 40 may be of the sameor different lengths. In certain embodiments, typically the first andsecond stage filter elements are about the same axial length (e.g.identical length or plus/minus about 10% difference in length).

With further reference to FIG. 1, extending concentrically from theannular guides 32 through the second stage 30 are a plurality of tubularflow diffusers 46. The second stage filter elements 40 each extendconcentrically with one of the flow diffusers 46 therethrough throughthe second stage 30. The flow diffusers 46 may be sized such that aselected clearance distance exists between the second stage filterelements 34 and the flow diffusers 46 when the second stage filterelements 34 are received therein. In one embodiment, and as will be morefully explained below, the flow diffusers 46 may act as coalescers tofurther coalesce contaminants from the fluid being filtered, and mayhelp to prevent the filtered fluid from being recontaminated uponexiting the second stage filter 40 into the second stage 30.

As illustrated in FIG. 1, the vessel 20 includes a head 48 selectivelyproviding access to the interior of the vessel 20 for changing thefilter elements 34, 40. To change the filter elements 34, 40, the head48 may be opened and either one or both of the filter elements 34, 40may be slidably removed and/or replaced.

In one embodiment, the vessel 20 also includes a pair of drain passagesin downcomers 50, 52 in fluid communication with the first stage 26 andconnected to a sump 54 for drainage and collection of solids andpre-coalesced liquids filtered from the fluid in the first stage 26. Thevessel 20 also defines a second drain passage via stage downcomer 56 influid communication with the second stage 30 and connected to the sump54. The sump 54 is divided into a first-stage compartment 58 and asecond-stage compartment 60 by an impermeable baffle 62 which isolatesthe first-stage compartment 58 from the second stage compartment 60.Also, various drains for selectively removing separated and coalescedfluids may be included.

With reference to FIG. 2, a second embodiment of a vessel 64 isillustrated. The vessel 64 is similarly divided into a first stage 26and a second stage 30 by the transverse partition 66. The transversepartition 66 defines a plurality of openings 68. A tubular filter guide70 is aligned with each opening 68 and extends longitudinally a selecteddistance from the partition 66 into the first stage 26.

The transverse partition 66 and the tubular filter guides 70 may beformed from plastic, metal, or any other suitable material known in theart, but are typically metal plate material. The tubular filter guides70 may be unitarily formed with the transverse partition 66 as a singlepiece or may be formed separately and attached to the transversepartition 66 by any suitable means, typically annular welds. Though onlya single opening 68 and tubular filter guide 70 is illustrated in FIG.2, it will be understood that any suitable number of tubular filterguides 70 and openings 68 in the transverse partition 66 may beprovided.

As in the previous embodiment, first stage filter elements 34 extendthrough the first stage 26 with their second ends 38 each disposedwithin a tubular filter guide 70.

As in the previous embodiment, the vessel 64 includes an inlet 22 influid communication with the first stage 26. The inlet 22 is locatednear the partition 66 such that as a fluid flows through the inlet 22into the first stage 26, the fluid impinges upon the filter guides 70.As such, the filter guides 70 aid in the removal of contaminants fromthe fluid while protecting the first stage filter element 34 disposedtherein.

With regard to the second stage 30, a screen member 72 is disposed in alower portion of the second stage 30. The screen member 72 extendssubstantially the length of the second stage 30 and acts as a barrier toprevent coalesced contaminants that have collected in the bottom of thevessel from becoming re-entrained in the fluid. The screen member 72 maybe formed from woven steel material or any other suitable material.

A plurality of basket shaped impingement baffles 74 are inserted throughthe tubular filter guides 70 and extend through the second stage 30. Thebaffles 74 may prevent liquids coalesced from the fluid from beingre-entrained in the fluid as the fluid flows through the second stage30. The baffles 74 include a basket portion 76 and a cap portion 78, aswill be more fully explained below. Second stage support screen 79 isdisposed in the second stage 30 and extends generally transverselythereacross. The screen 79 may be integrally connected to form a singlewebbed network. The screen 79 is spatially disposed within the secondstage 30 such that the fluid may flow unabated therethrough towards theoutlet 24. The screen 79 is configured to support the baffles 74 and thesecond stage filter elements 40. The screen 79 may be formed fromplastic, metal, or any other suitable material, but typically metal meshor perforated metal material.

The first ends 36, 42 of the filter elements 34, 40 and their supportwithin the vessel 64 are now further described.

As is illustrated in FIG. 3, the first ends 36, 42 of each of the firstand second stage filter elements 34, 40 each include end caps 80, 82.The end caps 80, 82 may be permanently connected to and each form afluid-tight seal with their respective filter elements 34, 40, such thatfluid must pass through the wall of each filter 34, 40 to reach thehollow core of each filter 34, 40. Each of the filter end caps 80, 82includes a post 84, 86 which tapers inwardly. In one embodiment, thepost 86 is of a different size than the post 84. As will be furtherexplained below, this differential sizing will easily allow a user todistinguish between the first stage filter element 34 and the secondstage filter element 40, as well as prevent accidental insertion of thefirst stage filter element 34 into the second stage 30.

The end caps 80, 82 may be formed from plastic, metal, a combinationthereof, or any other suitable material.

With reference to FIGS. 4 and 5, the cap portion 78 of a baffle 74 isillustrated. The cap portion 78 is generally cup-shaped with a pluralityof longitudinal slots 88 arranged around a cylindrical cup wall 90 andwhich terminate at a flat cup lid 92. A hollow basket cap portion post94, concentric with the cup wall 90 protrudes axially away from the cuplid 92. The basket cap portion post 94 defines a receiving space 95,configured to matingly receive the post 86 of the second stage filterend cap 82 when the second stage filter element 40 is inserted into theimpingement baffle 74. In one embodiment, due to the differential sizingof post 84 and post 86, the receiving space 95 will not receive post 84,as post 84 is too large to fit into the receiving space 95 and is largerthan post 86. Thus, a user would be prevented from accidentallyinserting the first stage filter element 34 into the second stage 30.

Returning to FIG. 2, when the second stage filter element 40 is receivedinto the impingement baffle 74, as in the previous embodiment, aclearance preferably exists between the impingement baffle 74 and thesecond stage filter element 40, typically between 0.10 and 0.40 inches.As will be explained further below, the impingement baffle 74 preventscontaminants coalesced or filtered from the fluid passing through thesecond stage filter element 40 from being re-entrained into the fluid.The impingement baffle 74 provides a mechanism for such contaminants tocollect and ultimately drain off into the second stage sump 60.

In one embodiment, the impingement baffle 74 may be integrally formedwith the second stage filter element 40 and inserted into or removedfrom the second stage 30 with the second stage filter element 40 as asingle piece. In another embodiment, the impingement baffle 74 and thesecond stage filter element 40 may be separately formed. As illustrated,the impingement baffle 78 and cap portion 74 are a separate componentapart from the second stage filter element 40. The end cap 82 of thesecond stage filter element 40 is slidably and removably received withinthe cap portion 74, with post and receptacle structures providinggenerally concentric location such that an annular space and gap isprovided between the outer periphery of the second stage filter element74 and the inner peripheral surface of the impingement baffle 78.

With further reference to FIG. 2, the second stage filter element 40 inan operative configuration extends from its first end 42 and cap 82 (seeFIG. 6) that is received within the cap portion 78 of the baffle 74.From there, the second stage filter element extends back toward thefirst stage through the second stage 30 within the baffle 74 and intothe tubular filter guide 70 into which it is received. The other end 44of the second stage filter element 40 is arranged proximate the secondend 38 of the first stage filter element 34, as will be more fullydescribed below.

Having described the basic structure of a pair of exemplary vessels 20,64 with which an embodiment of a multi-stage filter assembly 10 may beused, the general flow path of the fluid to be filtered will bedescribed.

With reference to FIG. 1, in the first embodiment, generally a fluidwill pass into the vessel 20 through the inlet 22 and into the firststage 26. The fluid will then be forced radially through the elementfrom the exterior to the interior hollow core of the cylindrical firststage filter elements 34. The fluid will then travel within the firststage filter elements 34 to the tubesheet 28. The fluid will then passfrom the interior of each first stage filter element 34 to the interiorof a respective cylindrical second stage filter element 40 and passwithin the core of the second stage filter element 40 into the secondstage 30. The fluid will then be forced radially outward from theinterior of the cylindrical second stage filter elements 40 to theexterior of the second stage filter elements 40 within the second stage30, and therefrom through the outlet 24 to exit the vessel 20. As willbe immediately apparent, filtering of the fluid will take place eachtime the fluid passes through one of the filter elements. Thus, thefluid in the flow path described above will undergo two stages offiltering. As will be discussed below, based on the type of filterelements 34, 40 selected, various types, amounts, etc., of contaminantsmay be filtered at each pass through each filter element 34, 40.

With reference to FIG. 2, in the second embodiment, fluid will enterthrough the inlet 22 and encounter the tubular filter guides 70 whichwill turn the fluid in the first stage 26 helping with an initialfiltering step. The fluid then will pass through the wall of the firststage filter elements 34 into the hollow core of these elements 34. Thefluid will pass from the cores of the first filter elements 34 into thehollow cores of respective second stage filter elements 40 within thetubular filter guides 70. The fluid will progress within the core of thesecond stage filter element 40 and exit through the wall of the secondstage filter element 40, pass through the impingement baffles 74, passpast the second stage support screen 79 and out through the outlet 24.

Such flow paths may be used for various suitable filtration, coalescing,and separation applications for various fluids. Other suitable flowpaths are also envisioned.

Various embodiments of multi-stage filter element assemblies 10 are nowfurther described below. The assemblies 10 are described as installed inthe second embodiment vessel 64 described above, but could be installedin the first vessel 20 or various other filtering apparatuses, as willbe recognized by one having ordinary skill in the art in light of thepresent disclosure.

As can be seen in FIGS. 6 and 6A, the first stage filter element 34 andthe second stage filter element 40 are sized and configured such thattheir second ends 38, 44 substantially abut in an assembledconfiguration, placing the interiors of the filter elements 34, 40 incontinuous fluid communication. The first stage filter element 34 andthe second stage filter element 40 are configured to surround and extendalong a longitudinal axis 96. The second ends 38, 44 of the filterelements 34, 40 may be laminated or otherwise secured together and notremovable from each other. Additionally, the second ends 38, 44 of thefilter elements 34, 40 may be configured such that the filter elements34, 40 are not permanently attached and may be readily removable fromone another. In other words, the filter elements 34, 40 may not beconnected and as such each filter element can be removed free and clearof the other filter element without further manipulation. Further, thehigh pressure in the inlet side exerts axial pressure on the firstfilter element to urge it into abutting relation with the first elementto maintain position without the need for connections therebetween.

Again with reference to FIG. 6A, a first ring seal holder 98 surroundsthe first stage filter element 34 proximate its second end 38. The firstring seal holder 98 is located between the first stage filter element 34and one of the tubular filter guides 70.

As may be seen in FIG. 6B, the first ring seal holder 98 carries anannular seal 100, in one embodiment a chevron-type seal. This is a typeof pressure actuated seal and can be a radial seal, wherein pressureacting upon the wiper/sealing annular flange portion may press it in togreater sealing relationship. The first ring seal holder 98 is generallyU-shaped, having a seal channel 102 and generally parallel legs 104,106. The seal channel 102 is configured to receive and carry the annularseal 100.

The annular seal 100 may be a chevron-type seal made of an elastomericmaterial, or any other suitable type of seal, such as a conventionalO-ring, and may be made of any suitable type of material. The annularseal 100 is releasably sealed and carried in the seal channel 102 by atension fit, but may be bonded or otherwise adhered in the seal channel102 or to the legs 104, 106 by any suitable means known in the art.

The chevron-type annular seal 100 includes a seal base portion 108, aseal vertex portion 110, and a seal cone portion 112. The seal baseportion 108 and the seal cone portion 112 are integrally joined at theseal vertex portion 110. The seal cone portion 112 may befrustoconically shaped. In one embodiment the seal base portion 108 andthe seal cone portion 112 form an angle α of about 60 degrees, thoughother angles are also envisioned, typically between 30 and 85 degrees.

As can be seen in FIG. 6A, the cone portion 112 extends in the upstreamdirection, with the chevron-type annular seal 100 and the first ringseal holder 98 forming a fluid-tight seal between the tubular filterguide 70 and the first stage filter element 34. The chevron-type annularseal 100 may be effective in high pressure applications due to itsability to maintain the fluid-tight seal under increased pressure due toits configuration.

The annular ring seal holder 98 may be formed from plastic such aspolyester and sealed and permanently affixed to the filter 34 insurrounding relation and sealed relation. The ring seal holder 98 may besealingly bonded to the filter 340 by a heat treatment, glue, adhesive,or any other suitable means. In one embodiment, the ring seal holder 98does not unnecessarily compress the filter 34. In other embodiments, thering seal holder 98 my be formed from any suitable material and may beremovable from the filter 34.

With further reference to FIG. 6A, a second ring seal holder 114surrounds the second stage filter element 40 proximate its second end 44and receives a second annular seal 116. The second ring seal holder 114and the second annular seal 116 are disposed between the second stagefilter element 40 and the tubular filter guide 70, providing afluid-tight seal between the second stage filter element 40 and thetubular filter guide 70. The second ring seal holder 114 and the secondannular seal 116 may be of a type described above in regards to thefirst ring seal holder 98 and the first annular seal 100, or may be ofany other suitable type.

Generally, the fluid pressure decreases downstream along the fluid path.The function of the pair of ring seal holders 98, 114 and annular seals100, 116 is further described with reference to FIG. 6.

The fluid within the second stage 30, having exited the second stagefilter element 40 may be at a lower pressure than the fluid entering thefirst stage 26. Therefore, by providing the first ring seal holder 98and the first annular seal 100, the fluid entering the first stage 26may be forced to pass through the first filter element 34 to the hollowcore of the first stage filter element 34 and prevented from enteringthe second stage 30 without being filtered.

Additionally, fluid within the hollow core of the first stage filterelement 34 and at the second end 44 of the second stage filter element40 may be at an intermediate but lower pressure than the pressureoutside of the first stage filter elements 34. As such, immediatelydownstream of the first ring seal holder 98 an annular chamber and space118 is provided for such intermediate pressure between the first ringseal holder 98 and the second ring seal holder 114. The second ring sealholder 114 and the second annular seal 116 are provided to prevent fluidthat has not passed through the walls of both the first and second stagefilter elements 34, 40 from entering the second stage 30, such as at theabutment seam between the first and second stage. Any gap formed betweenthe two elements 34, 40 at the abutment and proximity region istherefore not of consequence.

Thus, the second ring seal holder 114 and second annular seal 116 mayprovide a fluid-tight seal to prevent partially filtered fluid flowthrough only a portion and not the entire radial thickness of the secondstage filter element 40. The pressure within the space 118 between theseal holders 98, 114 and the annular seals 100, 116 will about equalizewith the pressure of the fluid within the hollow core and flow passageof the filters 34, 40—hence it is a generally static gas region inannular chamber and space 118. It is noted that the wiper flange of eachradial seal is directed in the same direction for pressure actuation.Thus the second seal 116 may be actuated by the intermediate pressureregion in space 118 to be pressed into greater radial seal relationshipduring operation.

The first and second ring seal holders 98, 114 and first and secondannular seals 100, 116 thus provide fluid and pressure isolation betweenthe first stage 26 and the second stage 30 of the vessel 64, preventingfluid from entering the second stage 30 without passing from theinterior to the exterior of one of the second stage filter elements 40,as well as preventing fluid from entering the interior of the secondstage filter element 40 or the second stage 30 without passing throughthe first stage filter element 34. Thus contamination of filtered fluidwith unfiltered or partially filtered fluid is avoided. The first andsecond ring seal holders 98, 114 may be configured any suitable axialdistance from one another. Further, to the extent the first stage filterelements 34 become spent prematurely and remaining capacity is left onthe second stage elements 40, the first stage elements 34 may be removedallowing for one stage operation, temporarily until the second stageelements 40 become spent. Additionally, in one embodiment, the spentfirst stage element 34 may be replaced leaving the second stage element40 in place for another cycle.

The materials of the first stage filter element 34 and the second stagefilter element 40 as described in relation to the first embodiment, andalso as may be used in other embodiments, are further described below.

Each of the first stage filter element 34 and the second stage filterelement 40 may be formed from the same or different types of filtermaterial or media, and may be the same or different types of filterelements. For example, both may include one or more layers of asurface-loading type media. More preferably, each is a depth-loadingtype of filter media having several layers of depth loading media.Alternatively, one may include a surface-loading type while the othermay include a depth-loading type of filter element. Each of the filterelements 34, 40 may be configured for coalescing and particulatefiltration, or each may include membrane-type filter media (e.g.,polymer films with specific pore ratings), nano-type filter media, orother filter media type known in the art. Thus, the first stage filterelement 34 may include any one of these or any other suitable type offilter media, while the second stage filter element 40 may also includeany one of these or any other suitable type of filter media. The filtermedia of the first and second stage filters 34, 40 may include the sametypes of filter media or may each include a different type of filtermedia. Thus, various different combinations of first stage and secondstage filter elements 34, 40 including various different combinations offilter media included in each may be used, providing for flexibility infiltering.

First and second stage filter elements 34, 40 work in conjunction toperform various filtration and separation operations. For example, inone embodiment, the first stage filter element 34 includes a depthtechnology media with a thickness ranging from 0.3 to 1.0 inches at aremoval level of 20 microns and larger designed to remove semi-solidtype contaminants, while second stage filter element 40 is a pleatedbarrier type media with a thickness range of 0.05 to 0.2 inches,designed to have a solids removal rating of from 1.0 to 10.0 microns.The combination of handling the semi-solid larger contaminants with adepth media followed by handling smaller contaminants with an absoluterated barrier filter media provides a two stage system in one housingthat may provide benefits over a single stage filter media, includinglonger life, while allowing for an absolute removal level down to from10.0 to 1.0 microns.

In one embodiment, a multi-stage vessel 20 may be configured to filter agaseous fluid. In another embodiment, a multi-stage vessel 20 may beconfigured to filter a liquid fluid. In one embodiment, second stagefilter element 40 is a membrane barrier. In another embodiment, secondstage filter element is a nano filter barrier configured to drop systemremoval levels down below 0.1 microns, thereby facilitating bacteriaremoval from various systems, e.g. water systems.

In one embodiment, a multi-stage vessel is configured for liquidseparation. The first stage filter element 34 includes a depthfiberglass media configured to facilitate moisture removal from ahydrocarbon fluid. The element 34 utilizes relatively highintermolecular polar attraction forces of fiberglass to trap andpre-coalesce water droplets under 1.0 microns in diameter. The secondstage filter element 40 includes a polymeric gradient depth media, forexample, the type of filter media marketed by the Perry EquipmentCorporation of Mineral Wells, Tex., under the PEACH mark. The secondstage filter element 40 serves as a water droplet growth media, therebyproducing droplets of a size that may eliminate the need for a secondaryseparator element.

In another embodiment, a multi-stage vessel is configured for liquidremoval from a natural gas fluid. The first stage filter element 34includes a hydrophobic fluorocarbon coated barrier configured to removeand collect water in the first stage sump 58 (illustrated in FIG. 2).The hydrophobic fluorocarbon coated barrier allows hydrocarbon liquidsto penetrate through the first stage filter element 34 and to travelthrough the interior of the first stage filter element 34 to theinterior of the second stage filter element 40. In this embodiment, thesecond stage filter element 40 includes a polymeric depth media, suchas, for example, the type of filter media marketed by the PerryEquipment Corporation of Mineral Wells, Tex., under the PEACH mark,which is configured to perform a hydrocarbon droplet coalescingoperation. Thus, upon the fluid passing through the second stage filterelement 40, pure, water free hydrocarbons are collected in the secondstage sump 60, while purified gas exits the outlet 24.

Herein liquid and gas applications are thus contemplated, and the word“fluid” is used to encompass both or other appropriate fluidpossibilities.

The filter elements 34, 40 may be of similar or dissimilar construction,with similar or dissimilar density, porosity, and other qualities. Thefilter elements 34, 40 may be configured for separation, coalescence,filtering, a combination of these, or any other suitable purpose.

As one example, the first stage filter element 34 may be configured tofilter solid particulates from the fluid being filtered, while thesecond stage filter element 40 may be configured to coalesce specificfluids from the fluid being filtered. Thus, many different pairs offilter elements 34, 40 suitable for various different applications areenvisioned.

As stated above, one envisioned type of filter element for use in thepresent invention may include the type of filter media marketed by thePerry Equipment Corporation of Mineral Wells, Tex., under the PEACHmark.

Additionally, in one embodiment, it is envisioned that filter media suchas that disclosed in U.S. Pat. No. 5,827,430, assigned to PerryEquipment Corporation of Mineral Wells, Tex., may be included in thefirst stage filter element 34 or the second stage filter element 40, orin both. One of the first or second stage filter element 34, 40 mayinclude such filter media while the other may include any other suitabletype of filter media. Additionally, it is envisioned that the firststage filter element 34 and/or the second stage filter element 40 mayinclude filter media formed by the methods disclosed in U.S. Pat. No.5,893,956, assigned to Perry Equipment Corporation of Mineral Wells,Tex.

Many different fluid types may be filtered, coalesced, separated, etc.,including liquids, gases, mixtures, suspensions, solutions, etc., usingmany different combinations of first stage and second stage filterelements 34, 40 and filter media.

As the first filter element 34 or the second filter element 40 may, inone embodiment, not be permanently attached, each may be changed outand/or replaced individually, without changing both filter elements 34,40, thus allowing for switching between various filtering applicationsand various pairings of filter element and filter media types.

Additionally, for example, should one of the filter elements 34, 40 wearmore quickly, this element 34, 40 may be replaced without replacing theremaining element 34, 40 that may have worn less quickly. Thus, varioustypes of fluids containing various types of contaminants may be filteredusing an embodiment of a multi-stage filter element assembly 10 in anexemplary multi-stage vessel 20.

With reference to FIGS. 6C and 6D, another embodiment is provided. Inthis embodiment, an annular internal element support core 85 extendsfrom the second end cap 82 through the interior of the second stagefilter element 40 and into the interior of the first stage filterelement 34. The annular internal element support core 85 generally linesthe interior of the second stage filter element 40 and a portion of thefirst stage filter element 34 proximate its second end 38. The annularinternal element support core 85 is perforated with holes to allow fluidflow therethrough, while providing support for the filter elements 34,40. Additionally, when the first stage filter element 34 is replaced, itmay be easily slid off of the annular internal element support core 85and the core 85 may serve as a guide for sliding the new first stagefilter element 34 in place.

The annular internal element support core 85 may be formed as a metalmesh structure, perforated sheet metal, or may be a porous plasticstructure, but may be any other suitable perforated or porous materialconfiguration known in the art. The annular internal element supportcore 85 may be permanently attached to the second end cap 82 and formedwith the second stage filter element 40 as a single member, may beselectively removable from the second end cap 82, may be unattached andconfigured in an abutting relationship with second end cap 82, or may beconfigured spaced apart from the second end cap 82. Additionally, theannular internal element support core 85 may be used in conjunction withany of the other embodiments presently disclosed.

With reference to FIGS. 7-7B, a second embodiment of a multi-stagefilter element assembly 10 is illustrated. In the second embodiment, thesecond end 38 of the first stage filter element 34 is disposed withinone of the tubular filter guides 70. With particular reference to FIGS.7A and 7B, a first ring seal holder 98 and first annular seal 100surround the first stage filter element 34 proximate its second end 38.The first ring seal holder 98 and first annular seal 100 are disposedbetween the first stage filter element 34 and the tubular filter guide70. The first annular seal 100 may be radially deflected and/orcompressed between the first stage filter element 34 and the tubularfilter guide 70, providing a fluid-tight radial seal. In one embodiment,a second ring seal holder 114 and a second annular seal 116 may surroundthe second stage filter element 40 proximate its second end 44. Thesecond ring seal holder 114 and the second annular seal 116 may bedisposed between and the second annular seal 116 may be radiallydeflected and/or compressed between the second stage filter element 40and the tubular filter guide 70, providing a fluid-tight radial seal.

In one embodiment, a ring divider seal end cap 119 is also provided,which may be securely affixed to either one of the filter elements. Thering divider seal end cap 119 encloses the second end 38 of the firststage filter element 34. The second stage filter element 40 extendscoaxially with the first stage filter element 34 (with the interiors ofthe filter elements 34, 40 in fluid communication along the hollow core,as in the previous embodiment). The second end 44 of the second stagefilter element 40 abuts the ring divider seal end cap 119 whichseparates the media of the first stage filter element 34 from that ofthe second stage filter element 40. The ring divider seal end cap 119may provide a seal between the filter media of the first stage filterelement 34 and the filter media of the second stage filter element 40while allowing fluid to travel from the interior of the first stagefilter element 34 to the interior of the second stage filter element 40.

In one embodiment, the ring divider seal end cap 119 includes an annular(e.g. cylindrical or conical to provide a tapered guide in) guideportion 120 extending transversely from a flat disc portion 121 of thering divider seal end cap 119. The flat disc portion 121 may besealingly bonded to the end of the tubular ring of filter media of thefirst filter element. The annular guide portion 120 is sized andconfigured to be surrounded by the second stage filter element 40, andto abut against the interior of the second stage filter element 40. Theannular guide portion 120 may help to slidably guide the first stagefilter element 34 as it is installed into an operative configurationrelative to the second stage filter element 40 and may help to maintainthe filter elements 34, 40 in alignment and in the operativeconfiguration. The annular guide portion 120 generally lines a portionof the second stage filter element 40. The annular guide portion 120 maybe integrally formed with a remainder of the ring divider seal end cap119 as a single piece. The annular guide portion 120 may be formed fromplastic, metal, an elastomer, or any other suitable material.

The ring divider seal end cap 119 may be formed from any suitable typeof material, including a plastic molded end cap, a urethane free risemolded end cap, etc. The ring divider seal end cap 119 may be secured tothe second end 38 of the first stage filter element 34 by any suitablemethod, including potting, forming a urethane end cap directly to thefilter media or in the case of plastic embedding the plastic into theend of the media (e.g. thermally welding) etc.

In an alternate embodiment, the ring divider seal end cap 119 mayinstead enclose and couple to the second end 44 of the second stagefilter element 40. In this alternate embodiment, the annular guideportion 120 may instead extend upstream from the ring divider seal endcap 119 into the interior of the first stage filter element 34 lining aportion of the second end 38 of the first stage filter element 34.

In an alternate embodiment, the ring divider seal end cap 119, mayeliminate the need for a second ring seal holder 114 and second annularseal 116. In this embodiment, the end cap 119 provides a fluid-tightseal between the filter media of the first stage filter element 34 andthe filter media of the second stage filter element 40. For example, thematerial of the seal end cap 119 may be compressibly resilient or carryan annular gasket (or annular seal protrusion that projects into end offilter media ring of the other stage). As such, in one embodiment only afirst ring seal holder 98 and first annular seal 100 may be provided.

With reference to FIGS. 7C and 7D, an alternate embodiment of the multistage-filter element assembly of FIGS. 7-7A is illustrated. In thisembodiment, the first ring seal holder 98 and first annular seal 100along with the ring divider seal end cap 119 provide a fluid tight sealwith respect to the second end 38 of the first stage filter element 34.Thus, in this second embodiment, only a single ring seal holder 98 andannular seal 100 are employed to ensure that fluid passes completelythrough both the first and second stage filter elements 34, 40.

With reference to FIGS. 8-8B, a third embodiment of a multi-stage filterelement assembly 10 is illustrated. As in the previous embodiment, aring divider seal end cap 119 a is provided, enclosing the second end 38of the first stage filter element 34. An annular guide portion 120 aextends transversely from a flat annular disc portion 121 a of the ringdivider seal end cap 119 a. The annular guide portion 120 a extendsalong the longitudinal axis downstream into the interior of the secondstage filter element 40. In one embodiment, the exterior surface of theguide portion 120 a may provided with a first threading structure 122.

The second end 44 of the second stage filter element 40 is provided withan end cap 124 enclosing and that may be sealingly bonded to the secondend 44 of the second stage filter element 40 (e.g. at flat disc portion125). Extending transversely downstream along the longitudinal axis froma disc portion 125 of the end cap 124 is an annular lining portion 126.The annular lining portion 126 is configured to abut against and line aportion of the second end 44 of the second stage filter element 40. Theannular lining portion 126 defines a second threaded portion 128 on itsradial exterior configured to cooperatively interact with the firstthreading structure 122 to releasably connect and secure the first stagefilter element 34 to the second stage filter element 40 in an operativeconfiguration. With this configuration, the first and second filterelements may be installed and removed as a single unit and assembly.

The first stage filter element 34 may be rotated about the longitudinalaxis 96, thereby engaging the first threading structure 122, locatedradially inwardly of the second threading structure 128 in the operativeconfiguration, with the second threading structure 128 until the end cap119 a of the first stage filter element 34 abuts the second end cap 126of the second filter element 40.

Optionally, an annular seal such as an elastomeric o-ring gasket may becarried by one of the end caps 119 a, 124 and compressed between theelements during operation providing an axial seal. This can negate theneed for the second seal 116 or alternatively the first seal 100. Axialcompression may be enhanced by the fact that the high pressure side maycause urge the elements together against the downstream side of thevessel. This axial seal feature may also be used without a connectionbetween elements such as by intermating threads as shown.

Like the first end cap 119 a, the second end cap 124 may be formed fromany suitable type of material, and preferably may be a plastic moldedend cap. The second end cap 124 may be secured to the second end 44 ofthe second stage filter element 40 by any suitable method, includingpotting, or embedding a plastic end cap directly to the end of thetubular ring of filter media. The annular lining portion 126 may beintegrally formed with the second end cap 124 as a single piece.

Various other suitable releasable coupling arrangements between thefirst stage filter element 34 and the second stage filter element 40 arealso envisioned, including various configurations that would allow useof only a single ring seal holder 98, 114 and single ring seal 100, 116and eliminate the need for a second ring seal holder 98, 114 and secondring seal 100, 116.

As in the embodiment illustrated in FIGS. 7C and 7D, in anotherembodiment, the first ring seal holder 98 and first ring seal 100 alongwith the first end cap 119 a may provide a fluid tight seal of thesecond end 38 of the first stage filter element 34, and thus, the secondring seal holder 114 and the second ring seal 116 are omitted.

With reference to FIGS. 9-9B, a fourth embodiment of a multi-stagefilter element assembly 10 is illustrated. In this embodiment, themounting post 84 of the first end cap 80 defines a receiving aperturecoaxial with the longitudinal axis 96 configured to receive a tie rod130. In one embodiment the receiving aperture may define threading. Thetie rod 130 is received within the receiving aperture, is supported bythe mounting post 84, and extends therefrom to a ring divider seal endcap 132 coupled to and enclosing the second stage filter element 40.

The second end 38 of the first stage filter element 34 is enclosed by anannular end cap 134 coupled to the first stage filter element 34 by anysuitable means such as adhesive, potting or thermally welding (all whichcan provide a seal bond). In an operative configuration, the first stagefilter element 34 is configured coaxial with and surrounding the tie rod130 with the annular end cap 134 configured in an abutting relationshipwith the ring divider seal end cap 132 and forming a fluid-tight sealtherebetween.

The ring divider seal end cap 132 is disposed within the tubular filterguide 70 and includes a ring seal receiving channel 136 containing aring seal 138, which may be a chevron-type seal or any other suitabletype of seal. The ring seal 138 may be compressed and forms afluid-tight seal between the tubular filter guide 70 and the ringdivider seal end cap 132. The ring divider seal end cap 132 may thus beremovably held in an operative configuration within the tubular filterguide 70.

With reference to FIGS. 9A and 9B, the ring divider seal end cap 132includes a pair of annular guide portions 140, 142 (that may becylindrical or slightly conical to provide tapered guide surfaces)extending transversely upstream and downstream respectively therefrom.The first annular guide portion 140 extends upstream from the ringdivider seal end cap 132 lining the interior portion of the second end38 of the first stage filter element 34 and the annular end cap 132. Thering divider seal end cap 132 thus may act as a guide to receive,support, and locate the second end 38 of the first stage filter element34 relative to the ring divider seal end cap 132 and the second stagefilter element 40, as the first stage filter element 34 may be slidablydisplaced onto the first annular guide portion 140. The first stagefilter element 34 may be easily slidably displaced off of the firstannular guide portion 140 for replacement with another first stagefilter element 34, which may in turn be easily slidably displaced ontothe first annular guide portion 140.

The second annular guide portion 142 extends upstream from the ringdivider seal end cap 132 into the interior of the second stage filterelement 40. The second annular guide portion 142 lines a portion of theinterior of the second end 44 of the second stage filter element 40supporting the second stage filter element 40 around the longitudinalaxis 96 and maintaining the interior of the second stage filter element40 in fluid communication with the interior of the first stage filterelement 34.

In the illustrated embodiment, the ring divider seal end cap 132 is anannular end cap creating a fluid tight seal on the second end 44 of thesecond stage filter element 40, while allowing fluid to flow from theinterior of the first stage filter element 34 to the interior of thesecond stage filter element 40. The ring divider seal end cap 132 may beformed from plastic, an elastomer, or any other suitable material. Thering seal 138 may be formed from an elastomer or any other suitablematerial capable of maintaining the ring divider seal end cap 132 inplace with respect to the tubular filter guide 70 and maintaining afluid-tight seal.

With further reference to FIG. 9B, the ring divider seal end cap 132includes a plurality of radially inwardly extending spokes 144 whichextend inwardly and meet at an annular hub 135. The annular hub 135defines threading on its interior wall configured to cooperativelyinteract with the threading of the tie rod 130. The center threadedportion 146 is configured to releasably cooperatively engage with thetie rod 130 to secure it. The tie rod 130 may, for example, includethreading configured to cooperatively engage the ring divider seal endcap 132. The tie rod 130 may threadingly interact with the ring dividerseal end cap 132 in an operative configuration to urge the first stagefilter element 34 towards and hold the first stage filter element 34 inan operative configuration with the ring divider seal end cap 132.Additionally, the ring divider seal end cap 132 may interface with thetie rod 130 in any other suitable manner.

An alternate end cap configuration is illustrated in FIGS. 10 and 11. Inthe alternate embodiment, the alternate first end cap 148 has a greaterdiameter than the first stage filter element 34 and includes an outerannular axially projecting portion 150 around its periphery. The end cap148 receives the tie rod 130 through its center and includes an axiallyprojecting center portion 152 which projects into the hollow core of thefirst stage filter element 34. The axially projecting center portion 152in one embodiment may have a diameter D no larger than the innerdiameter of the first stage filter element 34 axially proximate the endcap 148, may provide radial support for the first stage filter element34 and may serve to center the first stage filter element 34. The endcap 148 also defines an annular axial projection 154 located radiallyoutwardly from the projecting center portion 152 but radially inwardlyfrom the outer annular axially projecting portion 150. The outer annularaxially projecting portion 150 and the annular axial projection 154 maybe compressed into the first stage filter element 34 to prevent thefluid from escaping from within the first stage filter element 34 and toensure that the fluid passes entirely through the first stage filterelement 34.

The end cap 148 may be removed from the tie rod 130 by rotating the endcap 148 about the longitudinal axis 96. The first stage filter element34 may then be slidably placed over the tie rod 130. The end cap 148 maythen be threadably rotated about the longitudinal axis 96 onto the tierod 130 until the annular center portion 152 is located within thehollow core of the first stage filter element 34 and the first stagefilter element 34 is compressed against the outer annular axiallyprojecting portion 150 and the annular axial projection 150.

Various other suitable end cap configurations are also envisioned.

With reference to FIGS. 12 and 12A, a fifth embodiment of a multi-stagefilter element assembly 10 is illustrated. In this embodiment aprefilter is provide at the first stage, providing two stages offiltering at the upstream side, and thereby three stages of filteringoverall (e.g. three stages means at least three stages in that furtherprefilters or stages for additional capacity could be provided). In thisembodiment, an inner filter element 156 (which may be a single longfilter element providing two stages) extends from the first end cap 80through the first stage 26 through the tubular filter guide 70 into theimpingement baffle 74 through the second stage 30 to the second end cap82. A ring seal holder 98 holding a chevron-type or other suitable typeof ring seal 100 surrounds the inner filter element 156 and ispositioned between the tubular filter guide 70 and the inner filterelement 156, creating a fluid-tight seal therebetween.

An outer prefilter sleeve element 158 is also provided. The outer filterelement 158 surrounds the inner filter element 156 in the first stage 26and extends coaxially with the inner filter element 156 from the firstend cap 80 to the ring seal holder 98. Typically the prefilter sleeveelement 158 will be a more open, less restrictive and less efficientfilter media than the filter media of the inner filter element 156.Thus, little pressure drop is expected across the prefilter element,typically only about 0.1 to 0.2 PSI, while configured with an efficiencyto capture larger particles that are between one micron and 50 micronsin size.

Thus, in this embodiment, fluid passing through the first stage 26 willpass through the outer prefilter sleeve element 158, then through theinner filter element 156 into the interior of the inner element 156. Thefluid, thus having undergone two steps of filtering in the first stage26, will pass through the first stage 26 in the interior of the innerelement 156 through the tubular filter guide 70 and pass outwardlythrough the inner element 156 into the second stage 30 in a thirdfiltration step. Thus, the fluid will have undergone a three-stepfiltering process. The first stage may be a prefilter for largerparticles only, while the remaining two stages can provide depthfiltration for smaller particles. The second and third stages may haveequal filtration parameters, as is the case with a single continuousinner element as shown. Advantageously, the prefilter need only toextend a part of the length of the inner filter element and can increaselifespan of the inner filter element by capturing larger particles andwithout prematurely clogging or causing restriction due to the lowerefficiency and more open media. In one embodiment the addition of theouter prefilter sleeve element 158 will add a third level of coalescingto the system to increase liquid removal capability.

Moreover, the outer prefilter sleeve element 158 may be of a differentporosity and density, and may have various other differing qualities,than the inner filter element 156. In one embodiment, the outerprefilter sleeve 158 may be of a significantly larger porosity than theinner filter element 156 and may be configured to remove largecontaminants from the fluid.

The outer prefilter sleeve element 158 may also be used in combinationwith any of the other embodiments disclosed above, thus providing threeor more different stages of filtration. In such examples, preferably thelast stage will be the most efficient with the tightest pore sizes inthe media. In other embodiments, an outer filter sleeve element 158 maybe provided surrounding the first stage filter element 34 to againprovide a three step filtering apparatus. As in the embodimentillustrated in FIG. 12, the prefilter sleeve element 158 may extend overthe first stage filter elements through at least a portion of the firststage 26. Additionally, each of the first stage filter element 34, thesecond stage filter element 40, and the filter sleeve element 158 may beof similar or dissimilar types of filter elements formed from similar ordissimilar materials and have different porosities, densities, etc. Thismay provide for flexibility in filtering various different impuritiesfrom various fluids.

Additionally, in another embodiment, an additional outer filter sleeveelement 158 may be provided in surrounding relation with the secondstage filter element 40. Similarly, the additional outer filter sleeveelement 158 may be used in the second stage 30 in an embodiment having asingle inner filter element 156, or first stage and second stage filterelements 34, 40. It is also contemplated that a first outer filtersleeve element 158 could be provided surrounding the filter elementprovided in a first stage and a second outer filter sleeve element couldbe provided surround the filter element provided in a second stage.Moreover, it is contemplated that a single outer filter sleeve mayextend through both the first and second stages surrounding the filterelement or elements disposed therein. The additional outer filter sleeveelements may be of any suitable type, such as, for example, pleated orbarrier.

With reference to FIGS. 13-13B, an embodiment including an alternatering divider seal end cap 132 a is illustrated. The ring divider sealend cap 132 a includes a pair of annular guide portions 140 a, 142 a(that may be cylindrical or slightly conical to provide tapered guidesurfaces) extending transversely upstream and downstream respectivelytherefrom.

The ring divider seal end cap 132 a is disposed within the tubularfilter guide 70 and includes a ring seal receiving channel 136 acontaining a ring seal 138 a, which may be a chevron-type seal or anyother suitable type of seal. The ring seal 138 a may be radiallydeflected and/or compressed and forms a fluid-tight radial seal betweenthe tubular filter guide 70 and the ring divider seal end cap 132 a. Thering divider seal end cap 132 a may thus be removably held in anoperative configuration within the tubular filter guide 70.

In this embodiment, the ring divider seal end cap 132 a includes anannular axial gasket 174 installed in an annular receiving groove 170. Aradially outwardly projecting stepped portion 172 forms an upstream wallof the groove 172. The axial gasket 174 is disposed and retained withinthe groove 170 abutting the outwardly projecting stepped portion 172. Inan assembled configuration, the axial gasket 174 abuts the upstreamterminating edge of the tubular filter guide 70 and, with the steppedportion 172, forms a fluid tight axial seal with the tubular filterguide 70, preventing fluid flow around the divider seal end cap 132 aand into the tubular filter guide 70.

In one embodiment of a multi-stage filter element assembly, a tubularfilter guide may be flared outwardly at its upstream end. Thus, thegasket 170 and outwardly projecting stepped portion 172 configurationwill provide a fluid tight seal with such a flared tubular filter guide.

As in the previous embodiment illustrated in FIG. 9, the first annularguide portion 140 a extends upstream from the ring divider seal end cap132 a lining the interior portion of the second end 38 of the firststage filter element 34 and the annular end cap 132. The ring dividerseal end cap 132 a thus may act as a guide to receive, support, andlocate the second end 38 of the first stage filter element 34 relativeto the ring divider seal end cap 132 a and the second stage filterelement 40, as the first stage filter element 34 may be slidablydisplaced onto the first annular guide portion 140 a. The first stagefilter element 34 may be easily slidably displaced off of the firstannular guide portion 140 a for replacement with another first stagefilter element 34, which may in turn be easily slidably displaced ontothe first annular guide portion 140 a. The second annular guide portion142 a extends upstream from the ring divider seal end cap 132 a into theinterior of the second stage filter element 40. The second annular guideportion 142 a lines a portion of the interior of the second end 44 ofthe second stage filter element 40 supporting the second stage filterelement 40 around the longitudinal axis 96 and maintaining the interiorof the second stage filter element 40 in fluid communication with theinterior of the first stage filter element 34.

As in the previous embodiment, the ring divider seal end cap 132 a is anannular end cap creating a fluid tight seal on the second end 44 of thesecond stage filter element 40, while allowing fluid to flow from theinterior of the first stage filter element 34 to the interior of thesecond stage filter element 40. The ring divider seal end cap 132 a maybe formed from plastic, an elastomer, or any other suitable material.The ring seal 138 a may be formed from an elastomer or any othersuitable material capable of maintaining the ring divider seal end cap132 a in place with respect to the tubular filter guide 70 andmaintaining a fluid-tight seal.

With reference to FIG. 13B, as in the previous embodiment, the ringdivider seal end cap 132 a includes a plurality of radially inwardlyextending spokes 144 a which extend inwardly and meet at an annular hub135 a. The annular hub 135 a defines threading on its interior wallconfigured to cooperatively interact with the threading of the tie rod130. The center threaded portion 146 a is configured to releasablycooperatively engage with the tie rod 130 to secure it. The tie rod 130may, for example, include threading configured to cooperatively engagethe ring divider seal end cap 132 a. The tie rod 130 may threadinglyinteract with the ring divider seal end cap 132 a in an operativeconfiguration to urge the first stage filter element 34 towards and holdthe first stage filter element 34 in an operative configuration with thering divider seal end cap 132 a. Additionally, the ring divider seal endcap 132 a may interface with the tie rod 130 in any other suitablemanner.

With reference to FIGS. 14 and 14A, a seventh embodiment of amulti-stage filter element assembly is illustrated. In this embodiment,the second end 38 of the first stage filter element 34 is axially sealedby a first annular divider ring seal 190. The second end 38 of the firststage filter element 34 is coupled to the first annual divider ring seal190 by potting or by any other suitable method, with the first annulardivider ring seal 190 creating a fluid tight axial seal over the end ofthe first stage filter element 34 while allowing fluid passage throughthe interior of the first stage filter element 34 to the interior of thesecond stage filter element 40. The first annular divider ring seal 190includes a radially extending portion 192 axially sealing and projectingradially outwardly from the first stage filter element 34 and an axiallyextending flange portion 194 extending axially upstream from theradially extending portion 192 radially outwardly of the first stagefilter element 34. The first annular divider ring seal 190 also definesa step portion 196 radially outwardly of the first stage filter element34 and proximate the second stage filter element 40.

The second end 44 of the second stage filter element 40 is axiallysealed by a second annular divider ring seal 198. The second end 44 ofthe second stage filter element 40 is coupled to the second annulardivider ring seal 198 by potting or by an other suitable method, withthe second annular divider ring seal 198 creating a fluid tight axialseal over the end of the second stage filter element 40 while allowingfluid passage from the interior of the first stage filter element 40into the interior of the second stage filter element 40. The secondannular divider ring seal 198 includes a radially extending portion 200axially sealing and projecting radially outwardly from the second stagefilter element 40 and an axially extending flange portion 202 extendingaxially downstream from the radially extending portion 200 radiallyoutwardly of the second stage filter element 40. The second annulardivider ring seal 198 also defines a step portion 204 radially outwardlyof the second stage filter element 40 and proximate the first stagefilter element 34.

Thus, the first and second annular divider ring seals 190, 198 eachprovide axial sealing of the first and second stage filter elements 34,40. In one embodiment, the first and second annular divider ring seals190, 198 are formed from plastic. In other embodiments, the first andsecond annular divider ring seals may be formed from any other suitablematerial known in the art.

The radially extending portions 192, 200 of the first and second annulardivider ring seals 190, 198 are coupled together using adhesive, heatbonding, spin-welding or by any other suitable method for permanently orsemi-permanently joining, thus joining the first and second filterelements into a single length filter element. Thus, the coupled filterelements 34, 40 may be inserted or removed as a single piece.

The step portions 196, 204 of the first and second annular divider ringseals 190, 198 are opposed and face one another such that when the firstand second annular divider ring seals 190, 198 are joined, the stepportions 196, 204 form between them and each define half of an annularseal receiving notch 206 in which an annular chevron seal 208 is seated.The annular chevron seal 208 radially deflects or compresses to form afluid tight radial seal between the first and second annular dividerring seals 190, 198 and the tubular filter guide 70. The annular chevronseal 208 may be formed from an elastomer or any other suitable material.

The multi-stage vessel described herein is merely exemplary. Themulti-stage filter element assembly embodiments described may be used invarious different suitable applications. Additionally, although themulti-stage vessel has been shown in a generally horizontalconfiguration, it should be apparent that the multi-stage vessel may beconfigured in a generally vertical embodiment with the inlet portionlocated on the lower end and the outlet port located on the upper end.

For example, embodiments of multi-stage filter element assemblies inaccordance with the present invention may be used, for example, incoalescers such as those marketed by Perry Equipment Company of MineralWells, Tex., under the mark Gemini Purasep. Additionally, it isenvisioned that embodiments of multi-stage filter element assemblies inaccordance with the present invention may be used in conjunction withvarious other apparatuses in various filtering, separating, coalescing,and other suitable applications.

Various suitable materials for forming various multi-stage filterelement assembly embodiments are described above. In one embodiment, amulti-stage filter element assembly may be formed without the use of anymetal parts.

All references, including publications, patent applications, and patentscited herein are hereby incorporated by reference to the same extent asif each reference were individually and specifically indicated to beincorporated by reference and were set forth in its entirety herein.

The use of the terms “a” and “an” and “the” and similar referents in thecontext of describing the invention (especially in the context of thefollowing claims) is to be construed to cover both the singular and theplural, unless otherwise indicated herein or clearly contradicted bycontext. The terms “comprising,” “having,” “including,” and “containing”are to be construed as open-ended terms (i.e., meaning “including, butnot limited to,”) unless otherwise noted. Recitation of ranges of valuesherein are merely intended to serve as a shorthand method of referringindividually to each separate value falling within the range, unlessotherwise indicated herein, and each separate value is incorporated intothe specification as if it were individually recited herein. All methodsdescribed herein can be performed in any suitable order unless otherwiseindicated herein or otherwise clearly contradicted by context. The useof any and all examples, or exemplary language (e.g., “such as”)provided herein, is intended merely to better illuminate the inventionand does not pose a limitation on the scope of the invention unlessotherwise claimed. No language in the specification should be construedas indicating any non-claimed element as essential to the practice ofthe invention.

Preferred embodiments of this invention are described herein, includingthe best mode known to the inventors for carrying out the invention.Variations of those preferred embodiments may become apparent to thoseof ordinary skill in the art upon reading the foregoing description. Theinventors expect skilled artisans to employ such variations asappropriate, and the inventors intend for the invention to be practicedotherwise than as specifically described herein. Accordingly, thisinvention includes all modifications and equivalents of the subjectmatter recited in the claims appended hereto as permitted by applicablelaw. Moreover, any combination of the above-described elements in allpossible variations thereof is encompassed by the invention unlessotherwise indicated herein or otherwise clearly contradicted by context.

1. A multiple stage filter element assembly, comprising: a first filterelement comprising a first tube of filter media surrounding alongitudinal axis; a second filter element comprising a second tube offilter media surrounding the longitudinal axis when assembled with thefirst filter element, the first filter element adapted to axially abutthe second filter element with an internal flow passage therebetween; afirst seal element for the first filter element; a second seal elementfor the second filter element, the first and second seal elements beingadjacent each other and proximate an interface between the first andsecond filter elements when in abutting relation.
 2. The multiple stagefilter element assembly of claim 1, further comprising: a first end capenclosing one end of the first filter element, the first end cap havinga first locating post; a second end cap enclosing one end of the secondfilter element, the second end cap having a second locating post on anopposite side of the assembly as compared with the first locating post.3. The multiple stage filter element assembly of claim 1, wherein thefirst and second seal elements are in surrounding relation of the firstand second filter elements, respectively, the first and second sealseach being radial seals adapted for sealing against a common internalsurface of a cylindrical guide of a tube sheet.
 4. The multiple stagefilter element assembly of claim 3, wherein at least one of the firstand second tubes of filter media has an uncapped end surface at theinterface.
 5. The multiple stage filter element assembly of claim 3,wherein each the tubes of filter media has an uncapped end surface atthe interface.
 6. The multiple stage filter element assembly of claim 4,further comprising a first end cap sealing the end surface of one of thefirst and second tubes of filter media at the interface, the first endcap including a first annular guide portion extending transversely fromthe first end cap along a portion of the interior surface of the otherof the first and second tubes of filter media.
 7. The multiple stagefilter element assembly of claim 6, further comprising a second end capsealing the end surface of the other of the first and second tubes offilter media at the interface, the second end cap including a secondannular guide portion configured to cooperatively threadably engage thefirst annular guide portion of the first end cap.
 8. The multiple stagefilter element assembly of claim 1, wherein the first and second filterelements are arranged in axially abutting end to end relation and aremounted to each other.
 9. The multiple stage filter element assembly ofclaim 8, wherein the first and second filter elements are notpermanently attached but readily removable from each other.
 10. Themultiple stage filter element assembly of claim 1, wherein the first andsecond tubes each have a length of between 1 and 4 feet; and aregenerally cylindrical with an outer diameter of between 2 and 6 inchesand an inner diameter of between 1 and 5 inches.
 11. The multiple stagefilter element assembly of claim 1, further comprising a third filterelement comprising a third tube of filter media coaxial with andenclosing at least a portion of the first tube of filter media.
 12. Themultiple stage filter element assembly of claim 11, wherein the thirdtube of filter media is a type of filter media different than at leastone of the first tube of filter media and the second tube of filtermedia.
 13. A multiple stage filtration vessel, comprising: a closedvessel having a longitudinally extending length having an initially openinterior, an inlet at an extent and an outlet at an opposite extentthereof; a partition located within the vessel interior, the partitiondividing the vessel interior into a first stage and a second stage, agenerally cylindrical guide defining an opening in the partition; afilter element assembly, the filter element assembly extending throughthe opening, the filter element assembly having a hollow core whereinflow passage through the multiple stage filtration vessel is providedwhereby a fluid stream flows into the first stage through the inlet,into and through the hollow core of the filter element assembly back outthrough the filter element assembly into the second stage to the outlet;the filter element assembly comprising: an inner filter media tube andan outer filter media sleeve at the first stage, the outer filter mediasleeve surrounding the inner filter media tube, the outer filter mediasleeve being more open and porous than the inner filter media tube. 14.The multiple stage filtration vessel of claim 13, wherein at least oneof the outer filter media sleeve and the inner filter media tube is apleated filter member.
 15. The multiple stage filtration vessel of claim13, wherein the inner filter media tube and the outer filter mediasleeve each comprise non-pleated depth filtration medias having a radialthickness of at least 0.20 inches.
 16. The multiple stage filtrationvessel of claim 13, wherein the inner filter media tube extends a fulllength of a filtration chamber within the open interior between theextents, wherein the outer filter media sleeve extends a partial lengthonly to the partition, and wherein the multiple stage filtration vesselalso includes a seal sealing the filter element assembly to thegenerally cylindrical guide.
 17. The multiple stage filtration vessel ofclaim 13, wherein the filter element assembly includes a second filtermedia tube when assembled with the inner filter media tube, the secondfilter media tube adapted to axially abut the inner filter media tubewith an internal flow passage therebetween.
 18. A multiple stagefiltration vessel, comprising: a closed vessel having a longitudinallyextending length having an initially open interior, an inlet at anextent and an outlet at an opposite extent thereof; a partition locatedwithin the vessel interior, the partition dividing the vessel interiorinto a first stage and a second stage, a generally cylindrical guidedefining an opening in the partition; a filter element assembly, thefilter element assembly extending through the opening, the filterelement assembly having a hollow core wherein flow passage through themultiple stage filtration vessel is provided whereby a gas stream flowsinto the first stage through the inlet, into and through the hollow coreof the filter element assembly, back out through the filter elementassembly into the second stage to the outlet; the filter elementassembly comprising: a first filter element comprising a first tube offilter media surrounding a longitudinal axis; a second filter elementcomprising a second tube of filter media surrounding the longitudinalaxis when assembled with the first filter element, the first filterelement and the second filter element with an internal flow passagetherebetween through the hollow core; the first and second filterelements being independent and readily attachable and detachable fromeach other, each of the filter elements being directly or indirectlysupported by the generally cylindrical guide.
 19. The multiple stagefiltration vessel of claim 18, further comprising a ring divider sealend cap disposed between the ends of the first filter element and thesecond filter element and providing a fluid-tight seal therebetween, thering divider seal end cap including at least one annular guide portionextending transversely therefrom and configured to line a portion of theinterior of one of the first filter element and the second filterelement.
 20. The multiple stage filtration vessel of claim 19, whereinthe ring divider seal end cap includes a radially outwardly steppedportion and an axial gasket receiving groove including an axial gasketseated therein.
 21. The multiple stage filtration vessel of claim 18,further comprising an annular support core extending within at least aportion of the hollow core.
 22. The multiple stage filtration vessel ofclaim 18, further comprising a ring seal surrounding the first filterelement and a seal end cap disposed between the ends of the first filterelement and the second filter element, the ring seal and the end capproviding a fluid tight seal between the first stage and the secondstage.
 23. The multiple stage filtration vessel of claim 20, wherein thering seal is a chevron-type seal configured to maintain a fluid-tightseal between the cylindrical guide and the first filter element.
 24. Themultiple stage filtration vessel of claim 19, further comprising a tierod extending through the hollow core of at least a portion of the firstfilter element.
 25. The multiple stage filtration vessel of claim 18,wherein at least one of the density and the porosity of the first tubeof filter media is different from the second tube of filter media. 26.The multiple stage filtration vessel of claim 18, further comprising athird filter element including a third tube of filter media, the thirdtube of filter media configured coaxial with and surrounding at leastone of the first tube of filter media and the second tube of filtermedia.
 27. The multiple stage filtration vessel of claim 18, furthercomprising a third filter element including a third tube of filtermedia, the third tube of filter media configured coaxial with andsurrounding both the first and second tubes of filter media.
 28. Themultiple stage filtration vessel of claim 18, wherein an end of each ofthe first tube of filter media and the second tube of filter media areuncapped; wherein the ends are configured in an axially abuttingrelationship, and wherein a ring seal is configured between one of thefirst and second tubes of filter media and the cylindrical guide forminga fluid-tight seal therebetween.
 29. The multiple stage filtrationvessel of claim 18, wherein an end of at least one of the first andsecond tubes of filter media is provided with an end cap; and wherein anannular guide portion of the end cap extends into and lines a portion ofthe interior of the other of the first and second tubes of filter media.30. The multiple stage filtration vessel of claim 29, wherein each ofthe ends are provided with an end cap, and wherein the end caps areselectively cooperatively engageable to couple the first tube of filtermedia to the second tube of filter media.
 31. A filter element assemblyhaving at least three stages, for a pressure vessel having a tube sheetwith a plurality of openings, the filter element assembly comprising: atleast one internal filter element adapted to be installed through one ofthe openings, the internal filter element having a seal member disposedbetween the ends of the filter element assembly positioned for sealingagainst the tube sheet, the at least one internal filter elementproviding for two stages of filtration with a flow passage upstream ofthe seal member radially through filter media into a central passage andthen another stage radially outward through the media downstream of theseal; a prefilter element surrounding the at least one internal filterelement upstream of the seal to provide a prefilter stage upstream ofthe at least one internal filter element.
 32. The filter elementassembly of claim 31, wherein the at least one internal filter elementcomprises a full length continuous tube of filter media extendinglongitudinally on both sides of the seal member, the prefilter elementextending only a partial longitudinal length of the full lengthcontinuous tube.
 33. The filter element assembly of claim 32, whereinthe at least one internal filter element comprises at least two filterelements in abutting relation proximate the seal member including anupstream element generally on the upstream side of the seal member and adownstream element generally on the downstream side of the seal member,wherein the prefilter element surrounds the upstream element with thedownstream element generally not surrounding by the prefilter element34. The filter element of claim 31, wherein the seal member is a radialseal adapted to radially seal against the tube sheet.
 35. The filterelement of claim 34, wherein the radial seal is a pressure actuated sealand includes a pressure actuated flange adapted to be pressed by higherupstream pressure into tighter radial seal relationship when in use.